Isolation and Physicochemical Characterization of Starches from Three Varieties of Ethiopian Sweet Potato [Ipomoea batatas (L.) Lam.]
| dc.contributor.advisor | Gebremariam, Tsige (Professor) | |
| dc.contributor.author | Wondu, Kebede | |
| dc.date.accessioned | 2018-10-23T12:52:40Z | |
| dc.date.accessioned | 2023-11-06T08:09:04Z | |
| dc.date.available | 2018-10-23T12:52:40Z | |
| dc.date.available | 2023-11-06T08:09:04Z | |
| dc.date.issued | 2017-12 | |
| dc.description.abstract | Starch is a polysaccharide that has important role in pharmaceutical, food and other industries. Although there are a number of commercial sources of starch, it is important to evaluate the potential applications of starch from local sources. Despite the presence of different varieties of sweet potatoes in Ethiopia, the physicochemical properties of their starches have not been previously studied. Thus, the aim of this study was to isolate, characterize starches from three varieties of Ethiopian sweet potatoes, namely Awassa83, Kulfo and Tulla. Starches were isolated using 0.075% (w/v) sodium metabisulphite solution. The starches were studied for the amylose, lipid, protein, fiber, moisture content, granule size, morphology, X-ray diffraction pattern, swelling power and solubility, thermal properties, and pasting properties. Moisture, protein, ash, lipid and fiber content of the starches varied from 12.41 to 13.72%, 0.05 to 0.22%, 0.22 to 0.4%, 0.16 to 0.41% and 0.37 to 0.43%, respectively. Scanning electron microscopy showed polygonal, round and cupoliform/bell shaped granules and the starch from the sweet potato varieties differed in their mean granule size, particle size distribution and amylose content. While Kulfo starch showed highest amylose content (18.15%), starch from Awassa83 revealed the largest mean particle size (20.9 μm). Swelling power and solubility ranged from 14.5 g/g to 21.7 g/g and 3.05% to 9.8%, respectively. X-ray diffractions pattern of the starch was C-type with maximum characteristic peaks at 15o, 17o, and 23o 2θ. Gelatinization temperatures, namely, onset temperature (To : 61.82-65.27 oC), peak temperature (Tp: 65.60-69.09 oC), endset temperature (Te: 72.13-73.69 oC ) and the enthalpy of gelatinization (5.45 mJ/mg to 6.85 mJ/mg) were obtained. Variations in pasting properties were observed among the sweet potato starches comprising peak viscosity (787 mPa.s to 873 mPa.s), hot paste viscosity (652 mPa.s to 723 mPa.s), breakdown viscosity (135 mPa.s to 158 mPa.s), cold paste viscosity (898 mPa.s to 997 mPa.s), setback viscosity (111 mPa.s to 127 mPa.s), peak time (4 min to 4.53 min) and pasting temperature (71.85 oC to 74.3 oC). Awassa83 starch depicted relatively high Peak and breakdown viscosities and low setback viscosity, and it may be suitable as a thickening and gelling agent. In conclusion, the results indicate that the sweet potato starches may be alternative source for use in the food, pharmaceutical and other industries. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/123456789/13096 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | Addis Ababa Universty | en_US |
| dc.subject | Awassa83, Ipomoea batatas, Kulfo, Starch, Sweet potato, Tulla | en_US |
| dc.title | Isolation and Physicochemical Characterization of Starches from Three Varieties of Ethiopian Sweet Potato [Ipomoea batatas (L.) Lam.] | en_US |
| dc.type | Thesis | en_US |